The Activity of the Components of a Na–K–Cs System at High Temperatures

Abstract

The activity coefficients of the components of a Na–K–Cs ternary system in a temperature range of 773–1200 K are determined using the previously calculated thermodynamic properties, in particular, the activity of the components of binary alloys of alkali metals such as Na–K, Na-Cs, and K–Cs, at high temperatures [1–3]. The sides of the triangle of the phase diagram of this system are constituted by the binary Na–K, Na–Cs, and K–Cs binary alloys. The results obtained are used to calculate the saturated vapor pressure of the sodium–potassium-cesium eutectic (22.1 wt % K and 73.8 wt % Cs [4, 5]) in the same temperature range. The calculated data are in good agreement with the recommended reference data [6].